Exam 1 Revisions and Course Updates

• Exam 1 grades have been posted on Canvas
• Visit Student Hours to review your exam, or make an appointment
• Revisions can be made for ½ points back if done in office hours
• Revisions apply to Exam 1 only, to accommodate first exam jitters
• The last day to act is February 28th

Bonus Questions

• More in-class practice questions have been requested
• Lecture slides will be posted before future classes

Instructor Provided PowerPoint Slides

• Instructor-provided slides had no impact on class attendance
• There was an adverse impact on course performance for students using slides in their note-taking process

Access to Lectures

• Early access is desired to aid in note-taking, keeping track of where things are, and following along
• Early Access is desired to allow for instructor speed, and image use
• Slide numbers are desired too

Self-Reflection Assignment

• This Assignment is due this Friday
• It should consist of two paragraphs and be submitted on Canvas

Unit 2 Overview

• Week 5's topic is Phylogeny
• Week 6's topics are Phylogeny practice, Species, and Speciation
• Week 7's topics are Species and speciation and Adaptations to the environment
• Week 8 is set aside to catch up, review, and prepare for Exam 2

Systematics: Classifying Life on Earth

• Taxonomy involves the classification and nomenclature of organisms
• Phylogeny focuses on the evolutionary relationships of organisms and groups

Binomial Nomenclature

• Binomial nomenclature is a hierarchical classification system
• It organizes organisms into groups within groups

Systematics after Darwin

• Species evolve/change over time
• New species evolve from other species
• Taxonomy now aims to explain relationships and classify organisms

Phylogenetic Trees also called a Cladogram

• Phylogenetic trees arrange organisms based on common ancestry
• They serve as hypotheses for relationships between organisms
• Phylogenetic trees can be read from ancestor to descendant

How To Read a Phylogenetic Tree

• Phylogenetic trees indicate ancestral species and where splitting occurs called a node
• Phylogenetic trees show the unique and shared histories of the group

Phylogenetic History Evidence

• The premise is that related organisms share more characters
• Characters are traits, including:
  • Morphological traits
  • Physiological traits
  • Molecular traits

Phylogenetic Characters

• Characters (traits) and character states are used to construct phylogenies
• Character states are the "choices" for different traits
• Plesiomorphy refers to the ancestral character state, the oldest choice
• Apomorphy refers to a character state different than the ancestral state, a derived state

Character States

• Character states are often represented by "tick" marks along a lineage

Synapomorphy

• A synapomorphy is a shared derived trait
• It's a derived character state shared by two or more taxa
• Synapomorphies are homologous traits
• Symplesiomorphy is a shared "primitive" trait

Ancestral States

• Determining ancestral states is important
• The goal of phylogenetic classification is to determine monophyletic taxa called clades

Phylogenetic Groupings

• Monophyletic groupings include all descendants of a common ancestor
• Paraphyletic groupings include some of the descendants of a common ancestor
• Polyphyletic groupings include descendants but not a common ancestor

Convergent Evolution

• Convergent evolution is when two lineages evolve a similar trait independently from each other
• This is sometimes called Homoplasy or Analogous Traits

Incomplete Data

• Incomplete data complicates tree reconstruction
• Competing hypotheses seek to sort the data out
• The Principle of Parsimony declares that the simplest phylogenetic tree is generally the most accurate

Phylogenetic Trees and Cladograms

• Phylogenetic trees and cladograms represent a hypothesis about evolutionary relationships
• These relationships are ever-changing based on new discovered evidence
• Each branch point marks the divergence of two species

Phylogenetic Trees Information

• Phylogenetic trees show patterns of descent
• They do not show when species evolved or how much genetic change occurred in a lineage